1. Field of the Invention
The present invention relates to a closed-captioned digital television broadcast signal receiver.
2. Description of the Related Art
Conventionally, closed-captioned digital television broadcast signal receivers (hereinafter, abbreviated as digital TV receiver) extracts caption information from digital television broadcast signal (hereinafter, abbreviated as digital TV signal) and displays the caption information with superimposing it on an image of a TV program on a monitor screen of display apparatus.
In the United States, standards of the closed caption are established in EIA-608 and EIA-708, so that each TV station delivers TV signal in compliance with these standards for enabling to display the closed caption on the TV receivers.
Furthermore, Japanese Laid-Open Patent Publication No. 2003-9096 discloses another conventional TV receiver that can adjust various parameters which define a format for displaying the closed caption. For example, EIA-708 establishes a specification that a part of parameters can optionally be defined by a user through the TV receiver. In such parameters, font type, font size, foreground color, background color, edge color, edge type, foreground opacity, and background opacity are included. Each parameter further includes a plurality of selectable elements. In the digital TV receiver in compliance with EIA-708, the format of the closed caption can optionally be changed with adjusting these parameters.
Besides, the digital TV signal may include NTSC caption information formed in compliance with NTSC (National Television System Committee) system other than digital TV closed caption information in compliance with the digital TV system. Although the conventional digital TV receiver can extract the caption information from the digital TV signal and output the caption information which is superimposed on the image of TV program on the monitor display apparatus, it is difficult to the user to distinguish which of the digital TV caption information and the NTSC caption information is outputted on the monitor display. The digital TV system can allocate the data to the caption information much more than the NTSC system. Furthermore, the closed caption in compliance with EIA-708 can set various parameters on the user side. Thus, it is important to enable the distinction which of the digital TV caption information and the NTSC caption information is displayed on the monitor display in order to improve the operationality of the TV receiver.